The first reviews of the iPhone 4 on Verizon are out.The consensus? Verizon has more signal bars in more places than AT&T, with a main caveat: data speed is not as fast. So for millions of those who have threatened to jump the AT&T ship for what they think might be a more reliable carrier and for those who want a non-AT&T iPhone, here is your chance. Verizon and Apple have started taking pre-orders for existing customers for the iPhone 4.